// preload images
var img = new Array(16);

for (var i = 0; i < 16; i++ )
{
	img[i] = new Image();
}

img[0].src = "img/";
img[1].src = "img/";
img[2].src = "img/";
img[3].src = "img/";
img[4].src = "img/";
img[5].src = "img/";
img[6].src = "img/";
img[7].src = "img/";
img[8].src = "img/";
img[9].src = "img/";
img[10].src = "img"/;
img[11].src = "img/";
img[12].src = "img/";
img[13].src = "img/";
img[14].src = "img/";
img[15].src = "img/";

// swap image
function swapImage(imgName,imgNum)
{
	imgName.src = img[imgNum].src;
}

// swap object
function swapObject(topId,bottomId)
{
	var objTop = document.getElementById(topId);
	var objBottom = document.getElementById(bottomId);

	objTop.style.visibility = 'visible';
	objBottom.style.visibility = 'hidden';
}